Direct lift process apparatus

CROSS-REFERENCE TO RELATED APPLICATIONS

0001This application claims priority to U.S. Provisional Patent Application Ser. No. 62/012,159, filed on Jun. 13, 2014, which herein is incorporated by reference.

BACKGROUND

0002Field

0003Embodiments of the present disclosure relate to apparatus and methods for supporting and transferring substrates during photomask fabrication.

0004Description of the Related Art

0005Photomasks used in the patterning a substrate typically include a glass or quartz substrate having a patterned metal-containing layer. The patterned metal-containing layer is typically generated by etching with a radiation beam, such as a electron

0006Photolithographic photomasks typically comprise a substrate of an optically transparent silicon based material, such as quartz. A light-shielding layer of metal, typically chromium, is patterned on the surface of the substrate. The metal layer is patterned and etched to form features which define the pattern, and correspond to the dimensions of the features to be transferred to a substrate, such as a semiconductor wafer.

0007During deposition and etching processes employed to fabricate the photomasks, substrates are transferred and supported within a processing system. Photomasks are sensitive to defects, such as scratches, and particles, because defects and particles may alter the light transmission properties of the photomasks.

0008Therefore, there is a need for a method and apparatus for transferring and supporting substrates in processing systems with reduced defects and particle generation.

SUMMARY

0009Embodiments of the present disclosure relate to apparatus and methods for transferring and supporting substrates during photomask fabrication.

0010One embodiment provides a substrate support assembly. The substrate support assembly includes a substrate pedestal having an upper surface for receiving and supporting a substrate, a cover plate disposed on the substrate support pedestal, and two or more lift pins movably disposed through the substrate support pedestal and the cover plate. The cover includes disk body having a central opening. The central opening surrounds the upper surface of the substrate pedestal. Each of the two or more lift pins comprises one or more contact pads, and the contact pads of the lift pins extend into to the central opening of the cover plate to receive and support a substrate at an edge region of the substrate.

0011Another embodiment provides a process chamber. The process chamber includes a chamber body enclosing a chamber volume, a plasma source positioned to generate a plasma in the chamber volume, and a substrate support assembly disposed in the chamber volume. The substrate support assembly includes a substrate pedestal having an upper surface for receiving and supporting a substrate in the chamber volume, a cover plate disposed on the substrate support pedestal, wherein the cover plate includes a disk body having a central opening, and the central opening surrounds the upper surface of the substrate pedestal, and two or more lift pins movably disposed through the substrate support pedestal and the cover plate, wherein each of the two or more lift pins comprises one or more contact pads, and the contact pads of the lift pins extend into to the central opening of the cover plate to receive and support a substrate at an edge region of the substrate.

0012Another embodiment provides a method for supporting and transferring a substrate. The method includes raising two or more lift pins above a cover plate disposed around a substrate pedestal having an upper surface for receiving and supporting a substrate, wherein the cover plate has a central opening surrounding the upper surface, and each of the two or more lift pins has one or more contact pads extending into the central opening of the cover plate, receiving a substrate with the two or more lift pins by supporting the substrate at an edge region with the contact pads on the two or more lift pins, and lowering the two or more lift pins into lift pin recesses formed in the cover plate to transfer the substrate onto the upper surface of the substrate pedestal.

BRIEF DESCRIPTION OF THE DRAWINGS

0013So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this disclosure and are therefore not to be considered limiting of its scope, for the disclosure may admit to other equally effective embodiments.

0014<figref idref="DRAWINGS">FIG. 1A</figref> is a schematic sectional view of a process chamber according to one embodiment of the present disclosure.

0015<figref idref="DRAWINGS">FIG. 1B</figref> is a top view of the cover plate and the lift pins in the process chamber of <figref idref="DRAWINGS">FIG. 1A</figref>.

0016<figref idref="DRAWINGS">FIG. 1C</figref> is a schematic perspective view of the cover plate and the lift pins in the process chamber of <figref idref="DRAWINGS">FIG. 1A</figref>.

0017<figref idref="DRAWINGS">FIG. 1D</figref> is a schematic perspective view of the lift pins of <figref idref="DRAWINGS">FIG. 1A</figref> interacting with a substrate transfer robot blade.

0018<figref idref="DRAWINGS">FIG. 2</figref> is a schematic top view of a cover plate according to one embodiment of the present disclosure.

0019<figref idref="DRAWINGS">FIGS. 3A-3C</figref> are schematic perspective views of lift pins according to embodiments of the present disclosure.

0020<figref idref="DRAWINGS">FIG. 4</figref> is a schematic perspective view of a two-part lift pin according to one embodiment of the present disclosure.

0021To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one embodiment may be beneficially utilized on other embodiments without specific recitation.

DETAILED DESCRIPTION

0022The present disclosure generally relates apparatus and methods for handling photomasks, reticles or other substrates during fabrication. It should be noted that the terms “mask”, “photomask” and “reticles” may be used interchangeably to denote generally a substrate containing a pattern.

0023More particularly, the present disclosure relates to lift pins with reduced contact areas and a cover plate used in a plasma process chamber. The lift pins according to the present disclosure may include a mounting pole that is self supportive without requiring external supporting structure. The self supportive lift pins provide smooth and balanced movement and eliminate friction with additional supporting structure, thus reducing particle generation. The lift pins may include one or more contact pads for contacting substrates with reduced contact areas, thus reducing particle generation and lowering the possibility of scratching the substrate being handled. The cover plate of the present disclosure may be formed in one piece to improve uniformity in thermal coupling, improve radio frequency coupling and/or reduce particle generation.

0024<figref idref="DRAWINGS">FIG. 1A</figref> is a schematic sectional view of a process chamber <b>100</b> according to one embodiment of the present disclosure. The process chamber <b>100</b> may be a plasma etch chamber to process photomasks.

0025The process chamber <b>100</b> generally includes a chamber body <b>102</b>. The chamber body <b>102</b> may include chamber walls <b>104</b>, a chamber lid <b>106</b> and a chamber bottom <b>108</b>. The chamber body <b>102</b> defines a chamber volume <b>110</b> therein. The chamber walls <b>104</b> may have a slit valve opening <b>112</b> to allow a substrate handling robot <b>116</b> to pass therethrough for loading and unloading substrates. A slit valve door <b>114</b> may selectively open and close the slit valve opening <b>112</b>.

0026A substrate support assembly <b>118</b> is disposed in the chamber body <b>102</b> to support and transfer a substrate <b>122</b> during processing. The substrate support assembly <b>118</b> may include a substrate pedestal <b>120</b>. The substrate pedestal <b>120</b> may have an upper surface <b>130</b> to receive and support the substrate <b>122</b>. The upper surface <b>130</b> may be smaller than the substrate <b>122</b> being processed so that an edge region <b>123</b> of the substrate <b>122</b> extends beyond the upper surface <b>130</b> when the substrate <b>122</b> is positioned on the substrate pedestal <b>120</b>.

0027A cover plate <b>124</b> is disposed on the substrate pedestal <b>120</b>. The cover plate <b>124</b> may be disposed on a shoulder <b>125</b> of the substrate pedestal <b>120</b>. A central opening <b>132</b> of the cover plate <b>124</b> surrounds the upper surface <b>130</b> of the substrate pedestal <b>120</b>.

0028Two or more lift pins <b>126</b> may be movably disposed through the substrate pedestal <b>120</b> and the cover plate <b>124</b>. Each lift pin <b>126</b> may extend into the central opening <b>132</b> of the cover plate <b>124</b> to pick up the substrate <b>122</b> by the edge region <b>123</b>. The process chamber <b>100</b> includes a lift pin drive assembly <b>128</b> configured to move the two or more lift pins <b>126</b> vertically in the chamber volume <b>110</b>.

0029A plasma source <b>136</b> may be disposed over the chamber lid <b>106</b> for igniting and maintaining a plasma in the chamber volume <b>110</b>. The plasma source <b>136</b> may include one or more inductive coil elements <b>138</b>, <b>140</b>. The inductive coil elements <b>138</b>, <b>140</b> may be coupled to a power source <b>144</b> through a matching network <b>142</b>. The power source <b>144</b> may be capable of producing up to about 3000 W at a tunable frequency in a range from about 50 kHz to about 13.56 MHz. The substrate pedestal <b>120</b> may be coupled to a biasing power source <b>146</b> through a matching network <b>148</b>. The biasing power source <b>146</b> may include one or more radio frequency source, DC source or pulsed DC source to provide a biasing power to the plasma in the chamber volume <b>110</b>. Even though an inductive coupled plasma source is illustrated in <figref idref="DRAWINGS">FIG. 1A</figref>, the process chamber <b>100</b> may include other forms of the plasma source, such as capacitive coupled plasma source, remote plasma source, or microwave plasma source.

0030The process chamber <b>100</b> further includes a gas injecting assembly <b>150</b> configured to deliver one or more processing gases in the chamber volume <b>110</b>. In one embodiment, a gas source <b>152</b> may be coupled to the gas injecting assembly <b>150</b>. A vacuum pump <b>154</b> may be coupled to the chamber volume <b>110</b> through a valve <b>156</b>. The vacuum pump <b>154</b> may maintain a vacuum condition in the chamber volume <b>110</b> during processing.

0031A plasma screen <b>158</b> may be disposed round the substrate support assembly <b>118</b>. The plasma screen <b>158</b> includes a plurality of openings <b>160</b> to enable a uniform vacuum power around the substrate support assembly <b>118</b>. The plasma screen <b>158</b> may be formed from a conductive material to retain the plasma within an upper section of the chamber volume <b>110</b>.

0032The process chamber <b>100</b> may further include a shield <b>162</b> disposed above the substrate support assembly <b>118</b>. The shield <b>162</b> may be electrically isolated from the chamber body <b>102</b> and the substrate support <b>120</b>. The shield <b>162</b> includes a plurality of apertures <b>164</b>. The plurality of apertures <b>164</b> collectively provide an open area for controlling the amount of ions passing through.

0033The cover plate <b>124</b> may be formed in a unitary body to achieve improved thermal uniformity and RF uniformity and reduced particle generation in the process chamber <b>100</b>. Alternatively, the cover plate <b>124</b> may include multiple parts. As shown in <figref idref="DRAWINGS">FIG. 1A</figref>, the cover plate <b>124</b> may be a unitary plate with the central opening <b>132</b> formed through a central region. A unitary cover plate is advantageous over cover plates formed by two or more pieces. The unitary cover plate <b>124</b> equalizes surface charge across the substrate pedestal <b>120</b>, therefore, improving RF dielectric coupling uniformity. The unitary cover plate <b>124</b> provides improved thermal uniformity because there are not any interfaces within the cover plate <b>124</b> thus eliminating non-uniformity caused by non-uniform contact in the interfaces. The unitary cover plate <b>124</b> also improves thermal conductivities because of there are no interfaces. Furthermore, the unitary cover plate <b>124</b> also reduces particle generation because there are not any moving parts in the cover plate <b>124</b> to generate particles during processing.

0034The lift pins <b>126</b> of the present disclosure also reduce particle generation. Each lift pin <b>126</b> may include a solid mounting pole <b>134</b> to couple with the lift pin drive assembly <b>128</b> that is configured to move the lift pin <b>126</b> vertically in the chamber volume <b>110</b>. The solid mounting pole <b>134</b> eliminates the need of a bushing around the lift pin <b>126</b> during motion. By eliminating the needs of a bushing, the lift pins <b>126</b> achieve smoother and more balanced substrate handling and also reduce particle generation resulted from bushing. Each lift pin <b>126</b> may include one or more substrate contact areas (further discussed with <figref idref="DRAWINGS">FIG. 1B</figref>) for receiving and supporting a substrate thereon. The one or more substrate contact areas may be reduced to limit contact areas thus reducing particle generation from substrate contact.

0035The lift pin drive assembly <b>128</b> may be disposed outside the chamber body <b>104</b> below the chamber bottom <b>108</b>. In one embodiment, the lift pin drive assembly <b>128</b> may include an actuator <b>166</b> connected to a bracket <b>168</b>. The actuator <b>166</b> is configured to move the bracket <b>168</b> vertically. Two or more lift pin holders <b>170</b> may be in contact with the bracket <b>168</b> to move with the bracket <b>168</b>. Each lift pin holder <b>170</b> may extend through an inner volume <b>176</b> of a column <b>174</b> to couple with the solid mounting pole <b>134</b> of the lift pin <b>126</b>. A bellows <b>172</b> may be disposed around each lift pin holder <b>170</b> in the inner volume <b>176</b>. The actuator <b>166</b> moves the bracket <b>168</b> vertically, which then moves the lift pin holders <b>170</b> and the lift pins <b>126</b> vertically. Even though, the lift pin drive assembly <b>128</b> shown in <figref idref="DRAWINGS">FIG. 1A</figref> moves the two or more lift pins <b>126</b> together, suitable lift pin drive assemblies may be used to drive each of the two or more lift pins <b>126</b> individually.

0036<figref idref="DRAWINGS">FIG. 1B</figref> is a top view of the cover plate <b>124</b> and the lift pins <b>126</b> according to one embodiment of the present disclosure. The upper surface <b>130</b> of the substrate pedestal <b>120</b> may have a shape and dimensions that substantially match those of the substrate <b>122</b> being processed. In the embodiment shown in <figref idref="DRAWINGS">FIG. 1B</figref>, the upper surface <b>130</b> may be in a square shape for handling a square-shaped substrate. The upper surface <b>130</b> may be sized slightly smaller than the size of the substrate <b>122</b> so that the edge region <b>123</b> of the substrate <b>122</b> extends beyond the upper surface <b>130</b> of the substrate pedestal <b>120</b>. The central opening <b>132</b> of the cover plate <b>124</b> is also a squared shape. The cover plate <b>124</b> is disposed on the substrate pedestal <b>120</b> so that the central opening <b>132</b> is aligned with and centered about the upper surface <b>130</b>.

0037As shown in <figref idref="DRAWINGS">FIG. 1B</figref>, three lift pins <b>126</b><i>a</i>, <b>126</b><i>b</i>, and <b>126</b><i>c </i>are disposed through the cover plate <b>124</b>. In one embodiment, three recesses <b>178</b><i>a</i>, <b>178</b><i>b</i>, <b>178</b><i>c </i>may be formed in the cover plate <b>124</b> to receive the lift pins <b>126</b><i>a</i>, <b>126</b><i>b</i>, <b>126</b><i>c </i>respectively when the lift pins <b>126</b><i>a</i>, <b>126</b><i>b</i>, <b>126</b><i>c </i>are in a lowered position, as shown in <figref idref="DRAWINGS">FIG. 1A</figref>. At a raised position, the lift pins <b>126</b><i>a</i>, <b>126</b><i>b</i>, <b>126</b><i>c </i>extend above from the cover plate <b>124</b>.

0038Each lift pin <b>126</b><i>a</i>, <b>126</b><i>c</i>, <b>126</b><i>c </i>includes two contact pads <b>182</b> for contact with the substrate <b>122</b> at the edge region <b>123</b>. The contact pads <b>182</b> of each lift pins <b>126</b><i>a</i>, <b>126</b><i>b</i>, <b>126</b><i>c </i>extend inwardly from the recesses <b>178</b><i>a</i>, <b>178</b><i>b</i>, <b>178</b><i>c </i>into the central opening <b>132</b> of the cover plate <b>124</b>. The contact pads <b>182</b> may be arranged to provide a balanced support to the squared shaped substrate <b>122</b>.

0039The lift pins <b>126</b><i>a</i>, <b>126</b><i>b</i>, <b>126</b><i>c </i>may be of different shapes. In the embodiment shown in <figref idref="DRAWINGS">FIG. 1B</figref>, the lift pin <b>126</b><i>a </i>may be disposed along a first side <b>132</b><i>a </i>of the central opening <b>132</b>. The lift pin <b>126</b><i>a </i>is shaped to position the two contact pads <b>182</b> along the first side <b>132</b><i>a</i>. The two contact pads <b>182</b> of the lift pin <b>126</b><i>a </i>may be symmetrically positioned about a first axis <b>101</b> of the central opening <b>132</b>. The lift pin <b>126</b><i>b </i>may be position around a corner of a second side <b>132</b><i>b </i>and a third side <b>132</b><i>c </i>of the central opening <b>132</b>. In one embodiment, the lift pin <b>126</b><i>a </i>may be positioned along the first axis <b>101</b>.

0040The lift pin <b>126</b><i>b </i>may be shaped to position two contact pads <b>182</b> along the second side <b>132</b><i>b </i>and the third side <b>132</b><i>c </i>respectively. The lift pin <b>126</b><i>c </i>may be position around a corner of the third side <b>132</b><i>c </i>and a fourth side <b>132</b><i>d </i>of the central opening <b>132</b>. The lift pin <b>126</b><i>c </i>may be shaped to position two contact pads <b>182</b> along the third side <b>132</b><i>c </i>and the fourth side <b>132</b><i>d </i>respectively. In one embodiment, the contact pads <b>182</b> of the lift pins <b>126</b><i>b</i>, <b>126</b><i>c </i>may be symmetrical about the first axis <b>101</b>. In one embodiment, the lift pins <b>126</b><i>b</i>, <b>126</b><i>c </i>may be shaped in mirror image of one another.

0041<figref idref="DRAWINGS">FIG. 1C</figref> is a schematic perspective view of the cover plate <b>124</b> and the lift pins <b>126</b> showing the lift pins <b>126</b> in raised position. In the embodiment of <figref idref="DRAWINGS">FIG. 1C</figref>, the cover plate <b>124</b> has a step <b>180</b> formed in the central opening <b>130</b>. The step <b>180</b> may overlap with the edge region <b>123</b> of the substrate <b>122</b> to provide improved coverage over the substrate pedestal <b>120</b>. <figref idref="DRAWINGS">FIG. 1D</figref> is a schematic perspective view of the lift pins <b>126</b> relative to a substrate transfer blade <b>184</b> during substrate exchange. The substrate transfer blade <b>184</b> may belong to an external substrate handling tool, such as a robot, for transferring substrates in and out the process chamber <b>100</b>. At the substrate exchange position shown in <figref idref="DRAWINGS">FIG. 1B</figref>, the lift pins <b>126</b> may move vertically relative to the substrate transfer blade <b>184</b> to exchange a substrate with the substrate transfer blade <b>184</b>. In one embodiment, the substrate transfer blade <b>184</b> may include three fingers <b>186</b>. At the substrate exchange position shown in <figref idref="DRAWINGS">FIG. 1D</figref>, the three fingers <b>186</b> of the substrate transfer robot <b>182</b> are directed towards the three lift pins <b>126</b> respectively. Each finger <b>186</b> may be positioned between the two contact pads <b>182</b> of the corresponding lift pin <b>126</b>.

0042<figref idref="DRAWINGS">FIG. 2</figref> is a schematic top view of a cover plate <b>200</b> according to one embodiment of the present disclosure. The cover plate <b>200</b> may be used in place of the cover plate <b>124</b> in the process chamber <b>100</b>. The cover plate <b>200</b> may be disposed on a substrate support to cover portions of the substrate support not covered by the substrate to protect the substrate support from the process chemistry. The cover plate <b>200</b> may be formed in one or more pieces. The cover plate <b>200</b> when fabricated as a single piece of material provides improved thermal uniformity in thermal conductivity, improved RF couple uniformity during plasma processing, and reduced particle generation compared to cover plates formed from multiple pieces.

0043The cover plate <b>200</b> may have a disk body <b>202</b> having a central opening <b>204</b>. The central opening <b>204</b> may be a through hole with a straight sidewall. In one embodiment, the central opening <b>204</b> may be a through hole with stepped sidewalls. The disk body <b>202</b> may be substantially circular for covering a circular shaped substrate support. The central opening <b>204</b> may be a square to surround a square-shaped substrate <b>206</b>. Even though a circular cover plate with a square shaped central opening is described above, one piece cover plates that is non-circular or with a non-square shaped central opening may be used in non-circular process chambers or for processing non-square shaped substrates.

0044Lift pin recesses <b>208</b><i>a</i>, <b>208</b><i>b</i>, <b>208</b><i>c </i>may be formed on an upper side of the disk body <b>202</b>. The lift pin recesses <b>208</b><i>a</i>, <b>208</b><i>b</i>, <b>208</b><i>c </i>are shaped to receive lift pins so that contact areas of the lift pins are position under the substrate <b>206</b> during processing and allow the lift pins to rise above the cover plate <b>200</b> to pick up the substrate <b>206</b> during substrate exchange. The lift pin recesses <b>208</b><i>a</i>, <b>208</b><i>b</i>, <b>208</b><i>c </i>may be shaped to match the shape of the corresponding lift pins, such as lift pins <b>126</b><i>a</i>, <b>126</b><i>b</i>, <b>126</b><i>c </i>of the process chamber <b>100</b>. The lift pin recesses <b>208</b><i>a</i>, <b>208</b><i>b</i>, <b>208</b><i>c </i>allow the lift pins to be level with or recessed below the upper surface of the substrate pedestal, such as the upper surface <b>130</b> of the substrate pedestal <b>124</b>, when the lift pins are retracted in the cover plate <b>200</b>.

0045The lift pin recess <b>208</b><i>a </i>may be formed along a first side <b>204</b><i>a </i>of the central opening <b>204</b>. The lift pin recess <b>208</b><i>b </i>may be formed around a corner of a second side <b>204</b><i>b </i>and a third side <b>204</b><i>c </i>of the central opening <b>204</b>. The lift pin recess <b>208</b><i>c </i>may be formed around a corner of the third side <b>204</b><i>c </i>and a fourth side <b>204</b><i>d </i>of the central opening <b>204</b>. Each lift pin recess <b>208</b><i>a</i>, <b>208</b><i>b</i>, <b>208</b><i>c </i>may include one or more notches <b>210</b> connected to the central opening <b>204</b>. The one or more notches <b>210</b> allow contact pads of lift pins to extend into the central opening <b>204</b>. For example, the notches <b>210</b> may allow the contact pads <b>182</b> of the lift pins <b>126</b> into the central opening <b>204</b>.

0046A through hole <b>212</b> may be formed in each lift pin recess <b>208</b><i>a</i>, <b>208</b><i>b</i>, <b>208</b><i>c</i>. The through hole <b>212</b> is positioned to receive a mounting pole of a lift pin, such as the mounting pole <b>134</b> of the lift pin <b>126</b> described above. The through hole <b>212</b> allows the mounting pole of a lift pin to move vertically thus raising and lowering the lift pin. In one embodiment, the through hole <b>212</b> may include one or more flat surface <b>214</b> to provide alignment to the lift pin and prevent the lift pin from rotating about the mounting pole during vertical movement. The flat surface <b>214</b> may also function to maintain a predetermined orientation relative to the cover plate <b>200</b>.

0047The cover plate <b>200</b> may be formed symmetrically to improve process symmetry and/or uniformity. In one embodiment, the cover plate <b>200</b> is symmetrical about a central axis <b>201</b>.

0048The cover plate <b>200</b> may be formed from or coated with a material that is compatible with process chemistry and/or has suitable thermal properties and/or suitable electrical properties for the processes to be performed. For example, the cover plate <b>200</b> may comprise yttrium oxide (yttria), or a halogen containing plasma resistant material (HPM).

0049In one embodiment, the cover plate <b>200</b> comprises yttria. The cover plate may be formed from solid yttria. For example, the cover plate <b>200</b> may be formed by compacting yttria powder to a sample, sintering the sample, then machining the sintered sample into a desired shape and dimension. Alternatively, the cover plate <b>200</b> may include a yttria coating to reduce cost. The cover plate <b>200</b> may be formed by machining a base material, such as a metal, for example aluminum or stainless steel, to desired shape and dimension, and applying an yttria coating to the machined base material.

0050In another embodiment, the cover plate <b>200</b> comprises HPM. The HPM may yttrium oxide at a molar concentration ranging from about 50 mole % to about 75 mole %, zirconium oxide at a molar concentration ranging from about 10 mole % to about 30 mole %, and at least one other component, selected from the group consisting of aluminum oxide, hafnium oxide, scandium oxide, neodymium oxide, niobium oxide, samarium oxide, ytterbium oxide, erbium oxide, cerium oxide, and combinations thereof, at a molar concentration ranging from about 10 mole % to about 30 mole %. The cover plate may be formed from solid HPM by compacting articles of the HPM to a sample, sintering the sample, then machining the sintered sample into desired shape and dimension. Alternatively, the cover plate <b>200</b> may include a HPM coating to reduce cost. The cover plate <b>200</b> may be formed by machining a base material, such as a metal, for example aluminum or stainless steel, to desired shape and dimension, and applying a HPM coating to the machined base material.

0051<figref idref="DRAWINGS">FIGS. 3A-3C</figref> are schematic perspective views of lift pins according to embodiments of the present disclosure. <figref idref="DRAWINGS">FIG. 3A</figref> schematically illustrates a lift pin <b>300</b>. The lift pin <b>300</b> may be used in place of the lift pin <b>126</b><i>a </i>of the process chamber <b>100</b> and to fit with the lift pin recess <b>208</b><i>a </i>of the cover plate <b>200</b>. The lift pin <b>300</b> may include a head portion <b>302</b> and a mounting pole <b>306</b> extending downwardly from the head portion <b>302</b>. The head portion <b>302</b> may include contact pads <b>304</b> formed at a distal end of the head portion <b>302</b>. Each contact pad <b>304</b> may include a planar area for contacting a backside of an edge region of a substrate. The contact pads <b>304</b> may be minimized to reduce contact area thus reducing particle generation and improving thermal uniformity. In one embodiment, a side wall <b>305</b> may be formed adjacent the contact pad <b>304</b> to guide or provide alignment to the substrate.

0052The mounting pole <b>306</b> may be a linear shaft having a first end extending from the head portion <b>302</b> and a second end configured to connect with a lift pin drive assembly, such as the lift pin drive assembly <b>128</b> of the process chamber <b>100</b>. A drive adaptor <b>310</b> may be formed at the second end of the mounting pole <b>306</b> to connect the lift pin <b>300</b> with a lift pin drive assembly. In one embodiment, the mounting pole <b>306</b> may include at least one flat surface <b>308</b> that may be used for original alignment with a cover plate, such as the cover plate <b>200</b>. The flat surface <b>308</b> may also function to maintain the head portion <b>302</b> of the lift pin <b>300</b> in a predetermined orientation relative to the central opening of the cover plate.

0053The mounting pole <b>306</b> may be a solid shaft that provides enough rigidity so that the lift pin <b>300</b> is self supportive without needing any additional structures, such as a bushing, to provide support, alignment and/or balancing structures. The mounting pole <b>306</b> may be positioned in a location relative to the head portion <b>302</b> to improve balance when the lift pin <b>300</b> stands alone or supports a substrate at the contact pads <b>304</b>. In one embodiment, the lift pin <b>300</b> includes two contact pads <b>304</b>. The contact pads <b>304</b> are located on opposite sides of the mounting pole <b>306</b> to improve balance when supporting a substrate.

0054<figref idref="DRAWINGS">FIG. 3B</figref> schematically illustrates a lift pin <b>320</b>. The lift pin <b>320</b> may be used in place of the lift pin <b>126</b><i>b </i>of the process chamber <b>100</b> and to fit with the lift pin recess <b>208</b><i>b </i>of the cover plate <b>200</b>. The lift pin <b>320</b> may include a head portion <b>322</b> and a mounting pole <b>326</b> extending downwardly from the head portion <b>322</b>. The head portion <b>322</b> may include contact pads <b>324</b> formed at a distal end of the head portion <b>322</b>. Each contact pad <b>324</b> may include a planar area for contacting a backside of an edge region of a substrate. The contact pads <b>324</b> may be minimized to reduce contact area thus reducing particle generation and improving thermal uniformity. In one embodiment, a side wall <b>325</b> may be formed adjacent the contact pad <b>324</b> to guide or provide alignment to the substrate.

0055The mounting pole <b>326</b> may be a linear shaft having a first end extending from the head portion <b>322</b> and a second end configured to connect with a lift pin drive assembly, such as the lift pin drive assembly <b>128</b> of the process chamber <b>100</b>. A drive adaptor <b>330</b> may be formed at the second end of the mounting pole <b>326</b> to connect the lift pin <b>320</b> with a lift pin drive assembly. In one embodiment, the mounting pole <b>326</b> may include at least one flat surface <b>328</b> that may be used for alignment with a cover plate, such as the cover plate <b>200</b>, during installation.

0056The mounting pole <b>326</b> may be a solid shaft that provides enough rigidity so that the lift pin <b>320</b> is self supportive without needing any additional structures, such as a bushing, to provide support, alignment and/or balancing structures. The mounting pole <b>326</b> may be positioned in a location relative to the head portion <b>322</b> to improve balance when the lift pin <b>320</b> stands alone or supports a substrate at the contact pads <b>324</b>. In one embodiment, the lift pin <b>320</b> includes two contact pads <b>324</b>. The contact pads <b>324</b> are located on opposite sides of the mounting pole <b>326</b> to improve balance when supporting a substrate.

0057<figref idref="DRAWINGS">FIG. 3C</figref> schematically illustrates a lift pin <b>340</b>. The lift pin <b>340</b> may be used in place of the lift pin <b>126</b><i>c </i>of the process chamber <b>100</b> and to fit with the lift pin recess <b>208</b><i>c </i>of the cover plate <b>200</b>. The lift pin <b>340</b> and the lift pin <b>320</b> are mirror images of each other. The lift pin <b>340</b> includes a head portion <b>342</b> and a mounting pole <b>346</b> extending downwardly from the head portion <b>342</b>. The head portion <b>342</b> includes two contact pads <b>344</b>. A side wall <b>345</b> may be formed adjacent the contact pad <b>344</b> to guide or provide alignment to the substrate. A drive adaptor <b>350</b> may be formed at an end of the mounting pole <b>346</b>. The mounting pole <b>346</b> may include a flat surface <b>348</b> for alignment during installation.

0058In one embodiment, the lift pins <b>300</b>, <b>320</b>, <b>330</b> are each formed in one unitary piece to provide rigidity and eliminate any frictions between individual parts. The lift pins <b>300</b>, <b>320</b>, <b>330</b> may be formed from a material that is compatible with process chemistry and/or has suitable thermal properties and/or suitable electrical properties for the processes to be performed. For example, the lift pins <b>300</b>, <b>320</b>, <b>330</b> may comprise yttria or a HPM as described above. The lift pins <b>300</b>, <b>320</b>, <b>330</b> may be formed by compressing powder of yttria or HPM to form a sample, sintering the sample, and machining the sintered sample to achieve desired shape and dimension. Alternatively, the lift pins <b>300</b>, <b>320</b>, <b>330</b> may be formed by applying a yttria coating or HPM coating over a machined part formed from a base material, such as aluminum, stainless steel.

0059According to one embodiment of the present disclosure, the cover plate and lift pins may be formed from the same material to obtain substantially uniform thermal properties and/or electrical properties across the cover plate, therefore, improving process uniformity.

0060<figref idref="DRAWINGS">FIG. 4</figref> is a schematic perspective view of a two-part lift pin <b>400</b> according to one embodiment of the present disclosure. The lift pin <b>400</b> is similar to the lift pin <b>300</b> except that lift pin <b>400</b> includes a top portion <b>410</b> and a lower portion <b>420</b> joined together. As shown in <figref idref="DRAWINGS">FIG. 4</figref>, the top portion <b>410</b> and the lower portion <b>420</b> may be coupled together by fasteners, such as screws <b>408</b>. Alternatively, the top portion <b>410</b> and the lower portion <b>420</b> may be joined together by other means, such as by adhesives, or by welding.

0061The top portion <b>410</b> may include a body <b>412</b> having two contact pads <b>414</b> for receiving and supporting a substrate. The lower portion <b>420</b> may include a head <b>422</b> attached to the top portion <b>410</b> and a mounting pole <b>424</b> extending from the flat portion. The one or more fasteners <b>408</b> may secure the head <b>422</b> to the top portion <b>410</b>. A drive adaptor <b>426</b> may be formed at an end of the mounting pole <b>424</b>.

0062The top portion <b>410</b> and the lower portion <b>420</b> may be formed from the same material or different materials. The two-part configuration makes it easier to manufacture thus reducing cost. In one embodiment, the top portion <b>410</b> may be formed from yttria or HPM while the lower portion <b>420</b> may be formed from a base material to further reduce cost. Similarly, the lift pins <b>320</b> and <b>340</b> may also be formed from two parts to reduce cost.

0063While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.